1. Field of the Invention
The present invention relates to a method of manufacturing a storage electrode in a semiconductor device which can secure spacing between cells and prevent generation of bridges across cells.
2. Description of the Related Art
With a recent increase in the number of memory cells constituting a dynamic random access memory (DRAM) semiconductor device, the area occupied by each memory cell has gradually decreased. Meanwhile, a capacitor formed in each of the memory cells needs a sufficient capacitance for accurate reading of stored data. Accordingly, the current DRAM semiconductor device requires a memory cell with a capacitor having a large capacitance but which occupies a small area.
In a memory device having a capacity over 256M-bits, an inner cylinder type storage electrode is adopted to enhance the capacitance of a capacitor. FIGS. 1A through 1C are sectional views for explaining a conventional method of manufacturing an inner cylinder type storage electrode.
Referring to FIG. 1A, a first insulation film 11 is formed on a semiconductor substrate 10. The first insulation film 11 is etched such that the substrate 10 is partially exposed, thus forming a contact hole for a capacitor. A conductive film 12 for a storage electrode is formed on the surface of the contact hole and the upper surface of the first insulation film 11. Next, a second insulation film 13 is formed on the conductive film 12 so that the contact hole where the conductive film 12 is formed may be embedded. As shown in FIG. 1B, the surfaces of the second insulation film 13 and the conductive film 12 are sequentially etched such that the surface of the first insulation film 11 is exposed. Thus, the conductive film 12 is separated so inner cylinder type electrodes 12A and 12B for a storage electrode are formed.
Then, as shown in FIG. 1C, portions of the first and second insulation films 11 and 13 are removed by wet etching. By adjusting an etch selection ratio of the first and second insulation films 11 and 13, the etching is performed such that the first insulation film 11 outside the cylinder can remain at a predetermined height.
The above conventional method of manufacturing enlarges the surface area by growing the inner and outer walls of the cylinder by using a selective metastable polysilicon (SMPS) process with an undoped amorphous silicon thin film or a low-concentration doped amorphous silicon (a-Si) thin film. However, the design rule is decreased, and during such SMPS growing the thickness of the outer wall of the cylinder increases by 250-400 xc3x85. Thus, a sufficient process margin is not secured and a bridge is generated between the capacitors due to destroyed grains. Due to the above problems, conversion of the storage electrode into an inner cylinder or a crown cylinder has necessitated many process changes, and have made of device development more difficult.
Accordingly, the present invention is directed to a method of manufacturing a storage electrode in a semiconductor device that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
In accordance with the purpose of the invention, as embodied and broadly described, in one aspect the invention includes a method of manufacturing a storage electrode in a semiconductor device including forming a contact for a storage electrode in a poly oxide film formed on the semiconductor device and forming a first thin film thereon; forming a core oxide film and an anti-reflective coating film on the first thin film; forming a pattern by etching the anti-reflective coating film, core oxide film and the first thin film so that the poly oxide film is exposed; forming a second thin film on the overall resultant structure; forming a tungsten silicide layer on the second thin film; forming inner and outer walls of the storage electrode by blanket-etching the tungsten silicide film and the second thin film; removing the anti-reflective coating film and the core oxide film; performing a selective metastable polysilicon (SMPS) process so that different grain growths are generated at the inner and outer walls of the storage electrode; and forming a storage electrode by performing an annealing process in the storage electrode.
In another aspect, the invention includes a method of manufacturing storage electrodes including removing portions of an oxide film on a semiconductor device; forming a first thin film on the oxide film and the semiconductor device; depositing at least one layer over the first thin film; etching the at least one layer and the first thin film to define a pattern of structures; forming a second thin film on the pattern of structures; forming a tungsten silicide layer on the second thin film; forming inner and outer walls of the storage electrodes by etching away the tungsten silicide film and the second thin film over the pattern of structures; performing a selective metastable polysilicon (SMPS) process so that different grain growths are generated at the inner and outer walls of the storage electrodes; and annealing the first thin film.
In yet another aspect, the invention includes a storage electrode in a semiconductor device, including an oxide layer having a contact hole therein; a first thin film layer formed in the contact hole; an outer wall extending upward from the oxide layer and including tungsten silicide; and an inner wall adjacent to the outer wall and contacting the first thin film layer and including a second thin film, wherein the inner wall has an amount of grain growth, and the outer wall has a smaller amount of grain growth than the inner wall.
The present invention advantageously provides a method of manufacturing a storage electrode in a semiconductor device which can secure spacing between cells and prevent generation of a bridge by depositing amorphous silicon (a-Si) film on the inner wall of a cylindrical capacitor and tungsten silicide (WSix) film rich in silicon (Si), and performing a selective metastable polysilicon (SMPS) process to enlarge the surface area of the inner wall through a normal SMPS growing and form an uneven tungsten silicide film on the outer wall.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate one embodiment of the invention and together with the description serve to explain the principles of the invention.